Existing apparatus for sterilisation of polymeric articles suffer from various problems. In one form of previously known apparatus, polymeric articles are placed in bins on a conveyor which moves in a rectangular path around the radiation source. The articles, for example moulded polymeric products receive different doses of radiation dependent on their position within each bin. Articles in the middle of each bin are shielded by other articles. This may be of little importance in bulk sterilisation of non-organic materials but the effect on organic materials such as polymers is very dose dependent. Since the conveyor speed is set to give a specific dose, it is impossible to provide non-standard doses without modification of the plant which is usually used simultaneously for other purposes. It has also been common to use a turntable located in front of a radiation source. However articles in inner layers may be shielded by those in the outer layers. Because the available area for the turntable is finite, the quantity of articles which may receive even treatment is limited by the outside diameter of the turntable.